1. Field of the Invention
The present invention relates to an apparatus for measuring ozone component in the sample gas.
2. Description of the Prior Art
In the ozone measuring apparatus configured to determine the ozone component by the subtraction method by connecting the reference gas line for introducing reference gas with ozone removed by allowing the gas to pass the ozone decomposer and a sample gas line for introducing the sample gas as it is to an ozone analyzer via a selector valve and by introducing the reference gas and the sample gas alternately at specified intervals from both lines, there is an advantage of little interference effects because interference components are canceled each other.
For the above-mentioned ozone decomposer, various oxidation catalysts are used, but for example, when silver wool is used, the ozone decomposer is usually heated to about 170.degree. C. for reducing the interference caused by H.sub.2 O in the atmosphere for application.
However, at this level of temperature, oxidation reactions shown by ##EQU1## and reduction reactions shown by ##EQU2## take place, but the oxidation reaction of Eq. (1) is more conspicuous than the reduction reaction of Eq. (2), and adsorption of SO.sub.2 component occurs on the AgO surface.
Because there is a portion in which SO.sub.2 ultraviolet ray absorption spectrum overlaps ultraviolet ray absorption of ozone, if the SO.sub.2 component is contained in the sample gas, SO.sub.2 may be adsorbed to the ozone decomposer, causing a concentration difference of SO.sub.2 between reference gas and sample gas, and SO.sub.2 interference effects occur.